1. Field of the Invention
The present invention relates to write protection mechanisms for machine-readable data storage disks. More particularly, the invention concerns a write protection system for disks of a single or multiple disk cartridge, where write protection of any disk can be individually enabled or disabled while the disk and its cartridge are inserted into a disk drive.
2. Description of the Related Art
Many different schemes of "write protection" are used to prevent the writing of data to machine readable data storage disks. Certain floppy diskettes, for example, have flat, flexible jackets with one edge that defines a write protect notch. This type of diskette becomes a read-only diskette when a user covers the notch with an adhesive paper strip. As another example, many rigid diskettes have flat jackets with a two-position write-protect tab on one side. To activate this type of write protection device, a user slides the tab to a designated position.
In many applications, these conventional write protection schemes are satisfactory for their intended purposes. One advantage of these devices is that each diskette includes its own write-protect device. However, these devices are limited in certain other ways. For example, a user cannot access the write protection device of one of these diskettes while the diskette is inserted into a disk drive. The user therefore must remove the diskette from the drive to initiate write protection.
In addition to individual diskette protection, engineers have developed devices to write-protect multi-diskette cartridges. To operate a known cartridge-based write-protect device, a user activates a write protection device on the cartridge, thereby rendering the diskettes in the cartridge read-only. Unlike the individual diskettes described above, some conventional multi-diskette cartridges may be write-protected while inserted in a disk drive. With these cartridges, the write protection feature includes a selector that is positioned in the cartridge's face, which is exposed while the cartridge is inserted into a disk drive. Typically, the write protection is activated by pressing a button on the face of the cartridge. Despite this advantage, these cartridge systems are burdened with a different limitation than write protection devices designed for individual diskettes. Specifically, they do not permit users to individually write-protect diskettes contained in the cartridge. With the cartridge system, then, write protection is "all or none."